Head-mounted displays (HMDs) are known that are worn on the head of user for viewing video images and the like as described in PTL 1 through 3 below, for example.
Some of these HMDs have a mechanism for controlling whether or not for a user to visually recognize a forward view beyond a display block arranged in front of the eyes of the user. For example, some of HMDs of video see-through type with a camera mounted allow a user to visually recognize a forward view beyond a display block by displaying a video image obtained by taking the ahead of the display. Further, in the case of an HMD of optical see-through type having a display block of optical transparency, for example, a user is able to visually recognize a forward view beyond the display block by turning off a displayed video image. On the other hand, in the case where such video images of content as a video image, for example, representing a game play situation and a video image of a movie are displayed, a user cannot sometimes visually recognize a forward view beyond the display block.